AHF Active Harmonic Filter Application Case Compilation

Preface

An Active Harmonic Filter (AHF) is a power electronic device used for dynamically suppressing harmonics and compensating reactive power. Compared with traditional passive filters, AHF offers significant advantages including fast response, superior filtering performance, immunity to grid impedance variations, and the ability to filter multiple harmonic orders simultaneously. In recent years, with the widespread use of non-linear loads such as variable frequency drives (VFDs), rectifiers, and electric arc furnaces in industrial settings, the issue of grid harmonic pollution has become increasingly prominent, and the application of AHFs has grown accordingly.

With years of technical accumulation and industry experience, Shanghai Wenzheng Electric Co., Ltd. has provided power quality management solutions for numerous enterprises. This document compiles real-world application cases of the AHF Active Harmonic Filter across multiple industries, including the electronic chemicals, semiconductor, and chemical sectors, serving as a reference for professionals engaged in power quality management.

1. Electronic Chemicals Industry Case

1.1 Customer Background

Hebei Kainuo Zhongxing Technology Co., Ltd., established in October 2019, is a high-tech enterprise founded by a team of PhD-returned and other highly qualified researchers. Committed to green biochemical processes and sustainable development, the company is building a specialized production base for optoelectronic new materials and functional fine chemicals under the “Specialized, Precision, Innovative” philosophy.

1.2 Main Loads and Harmonic Sources

The production line of this enterprise uses a large number of variable frequency drives (VFDs). VFDs are typical non-linear loads that generate substantial harmonic currents during operation, primarily the 5th, 7th, 11th, and 13th characteristic harmonics. When injected into the power grid, these harmonic currents cause voltage waveform distortion, equipment overheating, and protective device maloperation.

1.3 Solution

After conducting a detailed on-site power quality analysis, the Wenzheng Electric technical team configured the AHF series Active Harmonic Filter for this enterprise. The solution features:

• Modular design with flexible capacity configuration, expandable based on actual harmonic levels
• Fast dynamic response with a full response time of less than 5ms, able to track and compensate harmonic currents within milliseconds
• Dual functionality for harmonic suppression and reactive power compensation in one unit
• Full-controlled power devices (IGBTs) for low losses and high efficiency
• Comprehensive protection including overcurrent, overvoltage, and over-temperature protection
• Intelligent functions such as CT reverse connection identification and phase sequence auto-adaptation for easy installation

1.4 Results

After installing the Wenzheng Electric AHF Active Harmonic Filter, the enterprise’s power distribution system harmonics were effectively managed. The Total Harmonic Current Distortion (THDi) was reduced from 28% to below 5%, with all power quality indicators meeting the requirements of national standard GB/T 14549. Production equipment operates more stably, equipment failure rates due to harmonics have decreased significantly, and production efficiency has been effectively ensured. The customer is highly satisfied with the treatment results.

2. Semiconductor Industry Case

2.1 Project Introduction

A semiconductor company in Wuxi is a high-precision continuous manufacturing enterprise. Semiconductor manufacturing processes have extremely stringent requirements for environmental cleanliness, temperature, humidity, and power supply quality. The entire facility demands very high power quality for production electricity. The production line uses numerous precision equipment that is highly sensitive to power quality.

2.2 Harmonic Problem Analysis

The semiconductor facility contains a large number of non-linear loads such as VFDs, UPS systems, and clean-room HVAC systems. The harmonic currents generated by these devices cause serious interference with precision semiconductor equipment, specifically:

• Harmonics cause voltage waveform distortion, affecting the normal operation of precision equipment such as lithography machines
• Harmonic currents cause additional heating in transformers and lines, reducing equipment service life
• Harmonic interference may cause control system malfunctions, affecting production continuity
• Harmonics cause neutral conductor overloading, posing safety hazards

2.3 Solution

The Wenzheng Electric technical team conducted a comprehensive power quality assessment of the semiconductor plant’s distribution system, precisely analyzed the harmonic characteristics of each major harmonic source, and developed a targeted AHF configuration plan:

• Installed Wenzheng Electric AHF at main distribution cabinets for localized compensation
• Uses three-phase four-wire connection to effectively filter zero-sequence harmonics including the 3rd order
• Configured intelligent monitoring system with 7-inch touchscreen HMI for real-time power quality data monitoring
• Reserved expansion interfaces for future capacity increases

2.4 Results

After project implementation, the semiconductor plant’s harmonics were comprehensively managed: Total Harmonic Voltage Distortion (THDu) was reduced from 8.5% to below 2%, and Total Harmonic Current Distortion (THDi) was reduced from 35% to below 5%, both well within national standard limits. The power distribution system operates more safely and reliably, the failure rate of precision equipment has significantly decreased, and both production line efficiency and product yield have improved.

3. Chemical Industry Case

3.1 Industry Characteristics

Huizhou Renxin New Materials Co., Ltd. is located in the Daya Bay Petrochemical Zone in Huizhou City. The company specializes in the production of polystyrene raw materials and is one of China’s leading manufacturers of general-purpose polystyrene. The chemical industry is a typical process industry with high requirements for production continuity and power supply reliability.

3.2 Harmonic Pain Points and Selection Process

As a typical chemical industry enterprise, Huizhou Renxin’s production process utilizes a large number of VFD loads. The 5th, 7th, 11th, and 13th harmonics generated by VFDs seriously affect the production process and pose significant safety risks. Notably, after experiencing unsatisfactory results with multiple brands of active filters that failed to fundamentally solve the harmonic issues, the company ultimately chose the Shanghai Wenzheng Electric AHF Active Harmonic Filter.

3.3 Technical Features of the Solution

The Wenzheng Electric AHF demonstrated the following technical advantages:

• Full response time of less than 5ms, capable of quickly tracking load changes
• Filtering efficiency exceeding 97%, effectively filtering harmonics from the 2nd to 50th order
• Intelligent functions including CT reverse connection identification and phase sequence auto-adaptation
• 7-inch touchscreen HMI for intuitive operation data monitoring
• Support for remote communication and centralized monitoring
• Modular parallel design for high reliability – single module failure does not affect others

3.4 Results and Customer Feedback

After installing the Shanghai Wenzheng Electric AHF Active Harmonic Filter, harmonic pollution was effectively managed. The Wenzheng Electric brand earned high praise and trust from the customer. In subsequent expansion and renovation projects, Renxin designated Wenzheng Electric as the sole supplier of AHF Active Harmonic Filters, demonstrating the customer’s high recognition of Wenzheng Electric’s product quality and technical capability.

4. Overview of AHF Applications in Other Industries

4.1 New Energy Industry Case

A new energy factory’s production process involves a large number of non-linear devices such as inverters and rectifiers. Shanghai Wenzheng Electric configured AHF Active Harmonic Filters and SVG Static Var Generators to effectively suppress harmonic resonance, improve power factor, and enhance power quality. After project implementation, the power factor increased from 0.72 to above 0.98, harmonic content was reduced to within national standard limits, and the annual electricity cost savings amounted to approximately RMB 150,000.

4.2 Water Treatment Industry Case

In a municipal wastewater treatment plant project, air blowers, lift pumps, and agitators extensively use VFD technology. The application of Wenzheng Electric AHF reduced harmonic content from THDi of 32% to 4.5%, ensuring continuous and stable operation of the water treatment process while reducing equipment failure rates and maintenance costs. The investment payback period was only 1.5 years.

4.3 Common Value of AHF Series Across Industries

• Effectively filters harmonics from the 2nd to 50th order, reducing THDi to below 5%
• Simultaneous reactive power compensation, improving power factor to above 0.99
• Fast response speed (full response <5ms), adapting to rapid load changes
• Modular design with flexible capacity expansion, up to 600A per unit
• Intelligent monitoring, convenient operation and maintenance
• Three-year full warranty and lifetime technical support

5. AHF Selection and Implementation Guide

5.1 Capacity Selection

The AHF capacity should be determined based on the on-site harmonic current levels. The general procedure is:

1. Use a power quality analyzer to conduct on-site measurements and determine the content of each harmonic order
2. Calculate the total harmonic current RMS value (THDi)
3. Apply a safety margin (typically 10%~20%) to determine the AHF rated compensation current

Shanghai Wenzheng Electric offers free on-site power quality testing services, with professional engineers conducting measurements using precision instruments and providing treatment proposals.

5.2 Installation Location

The AHF installation location should be determined based on the distribution of harmonic sources:

1. Centralized management: Install a large-capacity AHF at the main distribution board, suitable for dispersed harmonic sources
2. Local management: Install a small-capacity AHF near the harmonic source, suitable for concentrated harmonic sources
3. Hybrid management: Combine centralized and local approaches for balanced investment and effectiveness

5.3 Installation Precautions

1. The AHF should collect load current signals through CTs; ensure correct CT installation position and polarity
2. The AHF power supply should be taken from the filtering point; pay attention to phase sequence consistency
3. The AHF operating environment should be well-ventilated with ambient temperature not exceeding 40°C
4. Regularly inspect and maintain the AHF cooling system to ensure normal fan operation
5. Regularly review AHF operating data and address any abnormalities promptly
6. A comprehensive equipment inspection is recommended every six months

Conclusion

Shanghai Wenzheng Electric Co., Ltd. always adheres to the customer-oriented approach and technology-driven innovation, committed to providing high-quality and efficient power quality management solutions for customers across various industries. Since its launch, the AHF series Active Harmonic Filter has been successfully applied in numerous industries including electronics, semiconductor, chemical, new energy, water treatment, steel, textile, and healthcare, accumulating rich project experience.

We will continue to uphold our corporate spirit of “Steadfast and Pragmatic, Honest and Trustworthy,” continuously improving product quality and service levels to provide every customer with the best power quality management solutions. For more product information or to request a free power quality testing service, please feel free to contact Shanghai Wenzheng Electric Co., Ltd.